JPS6330866B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an inkjet recording device that ejects minute ink droplets in response to electrical signals and records an image using the ink droplets on recording paper.

Regarding an inkjet recording apparatus of a type in which an air flow is added to ink droplets, Japanese Patent Application Laid-open No. 82426/1983 is known.

FIG. 1 shows an inkjet recording apparatus having a mono-nozzle inkjet recording head with one ink discharge port, which is described in Japanese Patent Application Laid-Open No. 52-82426. As shown in the figure, the vibration source that converts electrical signals into vibrations consists of an electrostrictive element 1 and a diaphragm 2, and in response to the applied electrical signals, the pressure inside the ink chamber increases and ink droplets are ejected. do. The ink chamber includes an inner chamber 3 adjacent to the diaphragm 2 and an outer chamber 5 connected to the ink inflow passage 9.
It is divided into. These two chambers are connected to the connecting passage 4.
The passages 4 and the ink discharge ports 6 are connected to each other via a straight line.

An air outlet 8 is provided on the outside of the ink outlet 6, and the air flow sent from the air supply source 14 through the air flow path 10 passes through the air chamber consisting of the air supply groove 7 and the air supply layer 12, and the air is It constantly flows out from the ejection port 8 and helps the ink droplets ejected from the ink ejection port 6 in response to the electric signal 11 to fly. Note that 13 is an ink reservoir.

In the above inkjet recording device,
By keeping the thickness of the air supply layer 12 at 80 μm or less, the gradation of the recording device is improved and the threshold voltage is also lowered.

Furthermore, in the above-mentioned inkjet recording device, an air pressure regulating valve is used to apply an appropriate pressure to the ink reservoir so that ink droplets are not ejected from the ink ejection port by air flow only when no electrical signal is input. Adjustment means such as 15 and 16 are provided, but if the thickness of the air supply layer 12 is 81 μm or more, the air pressure adjustment valves 15 and 16 are not necessarily provided.
There is no need to provide such adjustment means.

FIG. 2 is a front view of the mono-nozzle inkjet recording head shown in FIG. 1, viewed from the air discharge port side.
The air flow sent through the air flow path 10 passes through the annular air supply groove 7, further passes through the disc-shaped air supply layer 12, uniformly flows into the air discharge port 8 from all directions, and the air discharge It is constantly flowing out from exit 8. However, the air supply groove 7 and the air supply layer 1
2 has a circular shape, so the mono-nozzle inkjet recording head has a large area when viewed from the front side on the air discharge port 8 side.

However, with such a conventional structure,
It is difficult to manufacture narrow, small, and lightweight mono-nozzle inkjet recording heads, and for this reason, when several mono-nozzle inkjet recording heads are used side by side, the total size of the heads becomes large and the weight is heavy. Since the load on the drive mechanism for scanning the mono-nozzle inkjet recording head increases, the number of mono-nozzle inkjet recording heads that can be installed in the inkjet recording apparatus is limited to a small number. Therefore, with the conventional structure, it is difficult to shorten the recording time by installing a large number of mono-nozzle inkjet recording heads.

FIG. 3 is a front view of a multi-nozzle inkjet recording head provided with a plurality of ink ejection ports, viewed from the air ejection port side. The air passes through the rectangular air supply layer 12 and flows uniformly from all directions to each air outlet 8-1, 8-2, . . . , 8-n.
1, 8-2, ... 8-n. All of the air discharge ports 8-1, 8-2, ..., 8-n are clogged with ink (ink clogging here means that ink accumulates in or near the air discharge ports, causing the air flow to become clogged). (This refers to a state in which the ejection of ink is obstructed.
Air flows out evenly from n, but air discharge ports 8-1, 8
-2..., at least one place among 8-n,
For example, if ink clogging occurs at the air outlet 8-2 in the figure, the airflow that should flow out from the air outlet 8-2 will flow out from other air outlets 8-1 and 8-3, for example. Therefore, like the mono-nozzle inkjet recording head shown in FIG. 2, where there is no other way for the airflow to escape,
-2 The ink clogging that occurs cannot be removed by air flow. In this way, in the conventional multi-nozzle inkjet recording head as shown in FIG. 3, it is impossible to remove ink clogging at the air ejection ports, and it is natural that normal recording characteristics cannot be obtained in a state where ink clogging occurs. difficult,
It is very difficult to always obtain normal recording characteristics.

The present invention solves the drawbacks of conventional inkjet recording heads, such as the difficulty in manufacturing a small, lightweight mono-nozzle inkjet recording head with a narrow width, and the inability to remove clogging of ink in a multi-nozzle inkjet recording head. The object of this invention is to provide an inkjet recording apparatus in which the multi-nozzle inkjet recording head is free from clogging.

An embodiment of the present invention will be described below with reference to the drawings.

4a and 4b are a front view and a side sectional view showing a mono-nozzle inkjet recording head which is the basis of an embodiment of the present invention. The air chamber consists of an air supply layer 12 and two air supply grooves 7 and 7', and an air outlet 8 and an ink outlet 6 are provided in the center of the air supply layer 12. The two air supply grooves 7 and 7' communicate with the air supply layer 12, respectively. Furthermore, two air supply grooves 7 and 7' are connected to each air supply source 1 via air channels 10 and 10'.
It communicates with 4. Note that the air supply layer 12 connects the mono-nozzle inkjet recording head to the air discharge ports 8.
When viewed from the side front, it has a slit-like shape that is long in the direction of air inflow and narrow in the direction perpendicular to the direction of inflow, and the width 18 in the perpendicular direction is more than four times the diameter of the air outlet 8.

The air flow sent from the air supply source 14 through the air flow path 10 flows through two air supply grooves 7 and 7'.
The air passes through the air supply layer 12 from two directions, and constantly flows out from the air outlet 8. In the air supply layer 12, the flow of air in the portion far from the air outlet 8 is mostly in the direction of air inflow, but the flow of air in the vicinity of the air outlet 8 is similar to that of the air outlet 8. It flows evenly from all directions. That is, the flow of the air around the air outlet 8 is the same as the flow of the air around the air outlet 8 in the conventional air supply structure of the annular air supply groove 7 and the air supply layer 12 shown in FIG. This is similar to the method described above, and sufficient recording characteristics can be obtained.

To explain in more detail, in order for the air flow near the air outlet 8 to flow uniformly from all directions with respect to the air outlet 8, it is necessary to The width 18 of
It must be at least 4 times the diameter of the air outlet 8. If the width 18 is less than 4 times, the air flow will flow more from the inflow direction into the air outlet 8, and from the direction perpendicular to the inflow direction. The inflow of airflow is small and the airflow is not uniform from all directions. That is, since the flow of air near the air outlet 8 becomes unstable, the flight direction of the ink droplets ejected from the ink outlet 6 becomes unstable, and the air flow near the air outlet 8 becomes unstable.
Since the collision occurs at or near the area, sufficient recording characteristics cannot be obtained.

In this way, the air supply layer 12 has a slit-like shape that is long in the inflow direction of the air flow, narrow in the direction perpendicular to the inflow direction, and the width 18 in the perpendicular direction is at least four times the diameter of the air outlet 8. It has been confirmed through experiments that good recording characteristics can be obtained by this method, and this shape also makes it possible to manufacture a small, lightweight mono-nozzle inkjet recording head with a narrow width.

5a and 5b are a front view and a side sectional view showing another mono-nozzle inkjet recording head which is the basis of an embodiment of the present invention. The air supply layer 12 is formed by half-etching a plate in which the ink discharge ports 6 are perforated.
2-2 and a thin air supply layer portion 12-1 near the ink ejection port 6, which is different from the one shown in FIG. Note that it is also possible to provide the air supply layer thick portion 12-2 by half-etching the plate in which the air outlet 8 is perforated.

The way the air flows is the same as that of the structure shown in Fig. 4, but since the cross-sectional area of the air supply layer thick wall portion 12-2 can be made large up to the vicinity of the air outlet 8, it is better than that of the structure shown in Fig. 4. Furthermore, a more uniform and stable air flow can be made to flow out from the air outlet 8.

6a and 6b are a front view and a side sectional view of a multi-nozzle inkjet recording head showing an embodiment of the present invention. Multiple air discharge ports 8-1, 8-2,
..., 8-n and ink discharge ports 6-1, 6-2,
..., 6-n, each air supply layer 12 is formed by several partition plates 17. The air discharge ports 8-1, 8-2, . . . , 8-n and the ink discharge ports 6-1, 6-2, . Each air supply layer 12 communicates with an annular air supply groove 7 , and the air supply groove 7 communicates with an air supply source 14 via an air flow path 10 . Note that each air supply layer 12 has a slit-like shape that is long in the inflow direction of the air flow, narrow in the direction perpendicular to the inflow direction, and the width 18 in the perpendicular direction is four times or more the diameter of the air discharge port 8. I am doing it.

An air flow supplied through the air flow path 10 from the air supply source 14 is fed into the annular air supply groove 7 . Furthermore, this air flow passes through the air supply groove 7,
Air is supplied from two directions and passes through each air supply layer 12, and constantly flows out from the air outlet 8. Here, the structure of the air supply groove 7 is annular, and has a large cross-sectional area and a large volume. Therefore, the air pressure inside the air supply groove 7 is uniform.
Uniform air pressure is applied to each air supply layer 12 from two directions. That is, a uniform air flow flows into each air supply layer 12 from the air supply groove 7 from two directions. Therefore, the flow of air in each air supply layer 12 is the same as in the case of the mono-nozzle inkjet recording head of the present invention shown in FIG.
8-2, . . . , 8-n as well.
In the case of FIG. 3, for example, if the air outlet 8-2 is clogged with ink, the air outlet 8-2
The airflow that should flow out more is from other air outlets, such as the air outlet 8.
Since the ink flows out from the air outlet ports 8-1 and 8-3, there is a major drawback in that it is not possible to remove ink clogging that occurs at the air outlet ports 8-2. However, with the structure shown in FIG. 6 of the present invention, for example, when ink clogging occurs in the air outlet 8-2, the air flow that should flow out from the air outlet 8-2 is divided into several air supply layers 12. Since the air is partitioned by the partition plate 17, the air does not flow out to the adjacent air supply layer 12, and therefore does not flow out from the air outlet 8-1 or 8-3, but flows out from the air outlet 8-2. Therefore, ink clogging can be easily removed by air flow.

As explained above, the present invention has a rectangular air supply layer and air flows in from both longitudinal directions of the rectangular shape, so that a small and lightweight mono-nozzle inkjet recording head with a narrow width can be constructed. Therefore, the recording time can be easily shortened by installing a large number of mono-nozzle inkjet recording heads. Furthermore, even if a multi-nozzle inkjet recording head is configured, stable recording can be performed without clogging as in the conventional case.

Note that, as for the shape of the air supply groove, in addition to each embodiment of the present invention, a structure in which a plurality of grooves are formed in each longitudinal direction of the air supply layer may be used.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the schematic structure of a conventional mono-nozzle inkjet recording device, FIG. 2 is a front view of the device, and FIG. 3 is a front view showing the schematic structure of a conventional multi-nozzle inkjet recording device. 4a and 4b are a front view and a side sectional view showing a mono-nozzle inkjet recording device which is the basis of the present invention, and FIG.
Figures a and b are a front view and side sectional view showing another example of the mono-nozzle inkjet recording device that is the basis of the present invention, and Figures 6a and b are front views showing an inkjet recording device in an embodiment of the present invention. and a side sectional view. DESCRIPTION OF SYMBOLS 1... Electrostrictive element, 2... Vibration plate, 3, 5... Ink chamber, 6... Ink discharge port, 7... Air supply groove, 8... Air discharge port, 9... Ink channel, 10
...Air flow path, 12...Air supply layer, 12-1...
... air supply layer thin wall portion, 12-2 ... air supply layer thick wall section, 13 ... ink reservoir, 14 ... air supply source,
17... Partition board.

Claims (1)

[Claims] 1. An air nozzle plate in which a plurality of air ejection ports of an inkjet recording head are arranged in a straight line and perforated therein, and an ink nozzle plate in which a plurality of ink ejection ports are perforated in opposition to the plurality of air ejection ports. partitioning the air supply layer formed between the adjacent ink ejection ports by providing a linear partition between the adjacent ink ejection ports;
A rectangular air supply layer arranged for each ink ejection port, and a plurality of rectangular air supply layers,
An inkjet recording device comprising an air supply groove that communicates in both longitudinal directions.